1. Field of the Invention
The present invention generally relates to image forming apparatuses. More specifically, the present invention generally relates to an image forming apparatus having a waste liquid tank configured to receive waste liquid generated by a maintaining and recovering operation of a recording head, the recording head being configured to eject liquid drops.
2. Description of the Related Art
As an image forming apparatus such as a printer, facsimile machine, copier, plotter, or a multiple function processing machine including the printer, facsimile machine, copier, and the plotter, an inkjet recording apparatus is known. The inkjet recording apparatus is a liquid ejection recording type image forming apparatus using a recording head configured to eject ink liquid drops.
In this liquid ejection recording type image forming apparatus, the ink liquid drops are ejected from the recording head onto a conveyed sheet so that image forming such as recording or printing is performed. In the liquid ejection recording type image forming apparatus, there are two kinds of image forming apparatuses. One is a serial type image forming apparatus configured to eject liquid drops so that an image is formed while a recording head moves in a main scanning direction. The other is a line type image forming apparatus using a line type head whereby liquid drops are ejected while the recording head does not move so that an image is formed.
Hereinafter, the “image forming apparatus” means an apparatus configured to eject liquid onto a medium such as a paper, thread, fiber, leather, hides, metal, plastic, glass, wood, or ceramic so that images are formed. The image forming apparatus includes a mere liquid ejecting apparatus. In addition, “image forming” means not only providing an image of characters, figures, or the like on the medium but also providing an image such as a pattern having no meaning on the medium. “Image forming” includes adherence of the liquid drops onto the medium.
Furthermore, “ink” is not limited to recording liquid or ink and any liquid that is a fluid when being ejected can be applied to the liquid such as fixing liquid. In addition, “sheet” is not limited to a paper but includes an OHP sheet or leather, for example. In other words, the sheet means a subject where the ink drops are adhered. The sheet includes a recorded medium, a recording medium, a recording paper, and a recording sheet.
In such an image forming apparatus (hereinafter “inkjet recording apparatus”), the ink is ejected from the nozzle so that recording is performed. Accordingly, degradation of ejecting capabilities of the recording head may be caused based on an increase of ink viscosity due to evaporation of a solvent from the nozzle, solidification of the ink, adherence of dust, mixture of bubbles, or the like. Because of this, the image forming apparatus has a maintaining and recovering mechanism configured to maintain and recover proper operation of the recording head.
For example, a cap (called a capping member, a cap member, or the like) configured to seal the nozzle of the recording head is provided in the image forming apparatus. By capping the recording head when the image forming apparatus is not being operated, drying or thickening of the ink in the nozzle can be prevented. In addition, during or before/after the recording operations, the ink drops which do not contribute to the recording operations are ejected so that the ink being dried or thickened in the nozzle is discharged, thereby recovering or maintaining ejecting capabilities.
Ejecting a liquid drop for maintaining the ejecting capabilities of the nozzle, which liquid drop does not contribute to image forming, is called preliminary ejecting or idle ejecting. Such a liquid drop is ejected to an exclusive idle ejecting receiver or the cap.
In the meantime, since the idle-ejected ink has a small drop amount and may be easily dried, thickened ink (ink having a high viscosity) may be easily formed. In addition, in a case where a stacked material made of the thickened ink is formed in the idle ejecting position so that the stacked material grows to a height reaching the recording head, degradation of ejecting the ink due to adhesion of the ink to the recording head may be caused or the recording medium may become dirty due to the ink adhered to the recording head being transferred to the recording medium.
The recording head is covered with a suction cap (cap member) so that a maintaining and recovering function (mechanism) is performed whereby the ink is removed from the recording head by the suction cap.
The waste liquid of the ink collected by the maintaining and recovering mechanism is discharged to a waste liquid receiver (waste liquid tank) having a suction member. Since the ink removed from the head has a relatively low viscosity but pigment ink includes solid contents such as pigment, a deposition due to drying of the ink is formed in an ink liquid drop area. More specifically, an ink stack such as a pillar is formed in a high temperature and low moisture atmosphere where the drying rate is relatively high.
Because of this, the waste liquid may overflow before space in the waste liquid tank is effectively used, and the service life time of the waste liquid tank may be shortened. In this case, in order to extend the service life time of the waste liquid tank, the height of the liquid tank may be extended. However, in this case, the size of the image forming apparatus becomes large and therefore there is a limitation to the extension of the height of the waste liquid tank.
A structure where relative positions of a discharge part of the ink and an exit path where the ink passes are changed by using a sublimation material such as a camphor and an elastic member such as a spring has been suggested, for example, in Japanese Laid-Open Patent Application Publication No. 2006-247880.
In addition, a structure where the ink is idle-ejected onto a movable member provided on the tank and the ink adhered to the movable member is scratched out by moving the movable member so as to be discharged to a place separated from the idle ejecting position has been suggested, for example, in Japanese Laid-Open Patent Application Publication No. 2005-199598.
Furthermore, a structure where there is a space at a bottom part in an ink discharge position of a waste liquid receiver so that a solvent is stored in the space and stacking is prevented, has been suggested, for example, in Japanese Laid-Open Patent Application Publication No. 2007-144904.
However, the above-mentioned related art image forming apparatus or the waste liquid receiver (waste liquid tank) has the following problems.
In the structure discussed in Japanese Laid-Open Patent Application Publication No. 2006-247880 where relative positions of a discharge part of the ink and an exit path where the ink passes are changed by using a sublimation material such as a camphor and an elastic member such as a spring, the sublimation material is sublimated if it has not been used for a long period of time, so that it is difficult to scatter the ink from the stacking position.
In the structure discussed in Japanese Laid-Open Patent Application Publication No. 2005-199598 where the ink is idle-ejected onto a movable member provided on the tank and the ink adhered to the movable member is scratched out by moving the movable member so as to be discharged to a place separated from the idle ejecting position has been suggested, the ink adhered to the movable member is discharged to the same portion and thereby the ink is stacked and fixed on the movable member and thereby the movable member may become not movable.
In the structure discussed in Japanese Laid-Open Patent Application Publication No. 2007-144904 where there is a space at a bottom part in an ink discharge position of a waste liquid receiver so that a solvent is stored in the space and stacking is prevented, the solvent may flow into the image forming apparatus at the time when the image forming apparatus is transported or provided.